It is therefore recommended that you reroll until you get an S-rank character. Although it is possible to play through the game with any character you are given, getting your hands on an S-rank character at the start of the game will make progressing the early part of your adventure in particular a lot easier.
The game employs the gacha method of obtaining new characters and weapons, so you are relying on luck as to what you get and when. Mega Man X DiVE has a huge roster of playable characters to collect, upgrade, and customize, and it is important that you invest your time and resources into one that is worthwhile.